The purpose of this work is to compare the quantity and time course of nystagmus induced by vestibular stimulation in normal and autistic children. The focus of work in progress is to analyze existing data on 21 autistic and 23 normal children. The data on all subjects include nystagmus responses to constant angular accelerations of 10 degrees/sec 2. The responses of many, but not all of these subjects, to accelerations of 5 degrees/sec 2, 2 degrees/sec 2, and 1 degree/sec 2 have also been recorded; work in progress also includes computation of these latter responses, and analysis of stimulus-response curves for all subjects for whom data are available on responses to several magnitudes of acceleration. Fifty seven nystagmus parameters are quantified from each subject's response to each magnitude of stimulation. These nystagmus parameters include average and peak amplitude, duration and velocity measures of the slow and fast components of the nystagmus beats during both the primary and the secondary nystagmus. In addition, the temporal progression of the nystagmus response is being analyzed in respect to change in response intensity from nystagmus beat to nystagmus beat in respect to time following the onset of stimulation. Work in progress also includes the recording of nonautistic mentally retarded subjects and normal infants in order to provide controls for the lower mental age (relative to chronologic age) which is characteristic of most autistic children.